Concrete

Tunnel Form Construction


Tunnel form CIP is a modern method of construction (MCC) of building cellular structures using reinforced concrete. The method combines the quality, speed, and accuracy of factory production with the flexibility of on-site building.

The Science of Salt

Deicing chemicals are the most common form of ice control and are necessary to prevent accidents and improve traction. Most of the time these chemicals are used without any thought toward the effect they have on the structure, surface, or roadway. Concrete in particular, can be significantly damaged by these chemicals.

Hot Weather Concreting

As the weather heats up it’s time to introduce hot-weather practices during concrete placement. Such practices typically involve using cooling mists, moist curing, retarding admixtures, low temperature mix water and even ice.

1000 Year Concrete

The idea of extreme durability concrete is not all that new, but advancements in processing are making long-life concrete more cost-effective.

The key to extreme durability is tight particle packing and very low porosity resulting in dense, low permeability concrete with very low creep potential.

Self-Desiccating Concrete

Moisture-related flooring problems have become a thorn in the sides of many  architects, contractors, and building owners. The failures are typically caused by left-over batch water (known as water of convenience) or moisture vapor from the subgrade. Groundwater is rarely a significant factor. The excess moisture vapor mixed with highly sensitive (that is, water-tight) floor coverings creates a situation where flooring materials blister, bubble and delaminate entirely.

Ductile Concrete

Not satisfied with plain-old or even see-through concrete? Ductile concrete may be what you’re looking for. Composed of fiber reinforced concrete with precisely controlled particle sizes, the material is able to transfer loads to adjacent, unloaded areas without breaking. This unique material is perfect for high-seismicity zones, is extremely durable and impermeable, and is ideal as a repair material.

Translucent Concrete

Concrete is among the most versatile and rapidly evolving construction materials. Highly specialized structural applications are common; but in recent years more and more fascinating non-structural uses have come into the industry.

One such product is translucent concrete. If you ever wished your walls or ceilings could be see-through, here you go… The material works by batching parallel strands of optical fiber into the concrete.

Concrete Spheres Store Energy

MIT researchers are developing an energy generation and storage system that combines wind turbines with 100 foot diameter, hollow, concrete spheres. The ORES system would operate in waters deeper than 650 feet, much deeper than present-day wind turbines. These turbines would float and be anchored to the sea-floor by multiple concrete spheres. The concept works by using wind-power generated when demand is low to pump water out of the spheres. When demand peaks, hydrostatic pressure would push water through a turbine generating electric power.

Beware of Concrete Blowups!

Actually, this phenomenon is extremely rare. Failures such as these tend to be caused by incompressible debris collecting inside unsealed joints, thus restricting thermal expansion.

Generally speaking, the volume of a concrete is greatest when it is fresh and decreases over time. This is why we install control joints into slabs to deal with the inevitable random cracking.

For a given concrete, drying shrinkage is at least 5.0x10-4  up to over 8.0x10-4 ; whereas the typical coefficient of thermal expansion is 5.5x10-6 (ACI 224R-01).

Tech Bulletin No. 2 MnDOT I-35W Bridge Replacement

Photo of the I-35 bridge spanning the Mississippi River. The bridge is painted bright white as part of the aesthetic  and artistic nature desired by the community and the designers.

Intended to replace the collapsed I-35 bridge and completed in late 2009, this 1200-foot long, 10-lane span consists of 120 box girder sections precast at the site and placed in 97 days. Many of the innovative features include bridge monitoring devices, such as strain gauges, chloride sensors, accelerometers, and inclinometers to measure the health of the bridge over time.

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